Spooky
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- Jun 1, 2013
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Just a quick note for anybody not familiar with the use of Sodium Hydroxide to strip anodise.(My apologies to those that use this stuff frequently)
Sodium Hydroxide aka Caustic Soda, causes an exothermic reaction when mixed with water, a few don't do's.
DON'T pour water into the Hydroxide pearls / crystals, always add crystals / pearls to the water.
DON'T add HOT water to hydroxide or hydroxide to hot water (it changes the reaction speed and can easily result in a steam explosion throwing hot hydroxide solution all over the place, you think this stuff is nasty cold, you want to see what it does when it's hot) A hydroxide reaction can easily reach 200 degrees, at that temperature water flash boils into steam and really can chuck this stuff a long way.
Concentrated Sodium Hydroxide has a burn factor of 9, Concentrated Nitric Acid has a burn factor of 6, Concentrated Sulphuric Acid has a burn factor of 5.
If the solution or crystals get on your skin or in your eyes, water...LOTS of water and keep the area irrigated for at least 20 minutes, then in the case of eyes go to the A&E department / Emergency Room of your local hospital and tell them what the contaminant is. Don't just give it a quick rinse off or you may find when your watching TV later that evening you get a burning sensation starting all over again.
1:2 Crystals / Water by volume will make a good strong mix that will strip both Caustic and Hard anodise in a matter of minutes.
Water isn't great at removing the solution from those nice expensive hosts in all the tight corners, when you have finished stripping remove the host from the solution, drop it into a container of vegetable or cooking oil. Agitate to make sure the oil has gotten into every tiny area of the host and leave overnight.
In the morning you will find that any remaining hydroxide has turned into a rather efficient soap and can be washed away with warm water. Same goes for the used solution, simply add cooking oil at a 3/1 Oil/Solution (by volume) and that evil gunk will all turn into soap overnight.
The usual rubber gloves used for dishwashing etc are no good for use with Caustic Soda, it will damage the structure of the gloves to a point your fingers will suddenly poke through them (not nice) so always use chemical rated gloves.
That's about it
My sincere apologies to the vast majority who already know this, I just wanted to be sure that no new members get badly burned when stripping anodise with Hydroxide.
best wishes
Dave
Sodium Hydroxide aka Caustic Soda, causes an exothermic reaction when mixed with water, a few don't do's.
DON'T pour water into the Hydroxide pearls / crystals, always add crystals / pearls to the water.
DON'T add HOT water to hydroxide or hydroxide to hot water (it changes the reaction speed and can easily result in a steam explosion throwing hot hydroxide solution all over the place, you think this stuff is nasty cold, you want to see what it does when it's hot) A hydroxide reaction can easily reach 200 degrees, at that temperature water flash boils into steam and really can chuck this stuff a long way.
Concentrated Sodium Hydroxide has a burn factor of 9, Concentrated Nitric Acid has a burn factor of 6, Concentrated Sulphuric Acid has a burn factor of 5.
If the solution or crystals get on your skin or in your eyes, water...LOTS of water and keep the area irrigated for at least 20 minutes, then in the case of eyes go to the A&E department / Emergency Room of your local hospital and tell them what the contaminant is. Don't just give it a quick rinse off or you may find when your watching TV later that evening you get a burning sensation starting all over again.
1:2 Crystals / Water by volume will make a good strong mix that will strip both Caustic and Hard anodise in a matter of minutes.
Water isn't great at removing the solution from those nice expensive hosts in all the tight corners, when you have finished stripping remove the host from the solution, drop it into a container of vegetable or cooking oil. Agitate to make sure the oil has gotten into every tiny area of the host and leave overnight.
In the morning you will find that any remaining hydroxide has turned into a rather efficient soap and can be washed away with warm water. Same goes for the used solution, simply add cooking oil at a 3/1 Oil/Solution (by volume) and that evil gunk will all turn into soap overnight.
The usual rubber gloves used for dishwashing etc are no good for use with Caustic Soda, it will damage the structure of the gloves to a point your fingers will suddenly poke through them (not nice) so always use chemical rated gloves.
That's about it
My sincere apologies to the vast majority who already know this, I just wanted to be sure that no new members get badly burned when stripping anodise with Hydroxide.
best wishes
Dave